Many circuits that incorporate a power switch comprise a current sensor for sensing the electrical current that passes through the power switch. A valve current regulation circuit may be one example of such a circuit. A power switch may be connected in series with a load. Information about the load current can thus be obtained by sensing the current that passes through the power switch. This information can be used to control and/or limit the load current, for example, or to detect when a certain current level is reached. Current sensing circuits comprising sense transistors are commonly used. However, such circuits may be inaccurate for high load currents because of matching issues between the power transistors and the sense transistors.